The code in chapter 7 of pro Drupal development has a bug.

The $instance array that you need to pass to field_create_instance() needs to be as below.

Drupal lets you add a taxonomy term to a node and if you use the GUI you can have a nice auto-complete widget that takes term name - and iof the term doesn’t exist yet you get a new term created when you save the node.

I wanted to access the same functionality on node I am generating from external data.